A temperature responsive fluid flow throttling means

ABSTRACT

An automatic, self-modulating, gas-fired, gas-powered, forcedcirculation residential or other hot water heating system, which is fully and efficiently operable without electricity or any other form of externally supplied power, other than the natural or other gas used for combustion, and includes a zone temperature-responsive control system which likewise requires no electricity or other external source of power.

United States Patent Inventor Walton W. Cushrnan 36483 Gloucester Drive.Fraser, Mich. 48026 App]v No 8,209

Filed Feb. 3, 1970 Division of Ser. No. 714,649. Pat. No. 3,514,034.

Patented June 29, 1971 A TEMPERATURE RESPONSIVE FLUID FLOW THROTTLINGMEANS 7 Claims, 8 Drawing Figs.

US. Cl 236/98, 251/5, 236/99 Int. Cl G05d 23/12 Field of Search 236/98,99; 251/4-7 [56] References Cited UNlTED STATES PATENTS 2,100,70911/1937 Crone 236/99 2,124,633 7/1938 Robinson.... 1. 236/99 2,241,0865/1941 Gould 236/99X 3,252,227 5/1966 Fleer 236/98UX PrimaryExaminer-Edward J. Michael Attorney-Lon H. Romanski ABSTRACT: Anautomatic, self-modulating, gas-fired, gaspowered, forced-circulationresidential or other hot water heating system, which is fully andefficiently operable without electricity or any other form of externallysupplied power, other than the natural or other gas used for combustion,and includes a zone temperature-responsive control system which likewiserequires no electricity or other external source of power.

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A TEMPERATURE RESPONSIVE FLUID FLOW THROTTLING MEANS RELATED APPLICATIONThis application is a division of my copending application Ser. No.714,649 filed Mar. 20, l968, entitled Gas-Fired and Powered HeatingSystem" now US. Pat. No. 3,514,034.

BRIEF SUMMARY OF THE INVENTION This invention relates generally to hotwater heating systems, and more particularly to such systems wherein anysuitable gaseous fuel is fired in a combustion chamber associated with ahot water boiler construction wherein the temperature of the water issubstantially elevated prior to its being force-circulated within asubstantially closed system to thermal radiation devices where most ofthe heat is released prior to its return to the boiler assembly forreheating and recirculation.

In most such installations, current practice requires the use of one ormore electrically or otherwise mechanically driven pumps to provide thenecessary hot water circulation, along with some form ofelectromechanical or electrothermal valving or zone circuitry andgas-burner control, including certain safety controls. This inventioncontemplates the complete elimination of the need for electricity as asource of power, either for hot water circulation or to activate thecontrol system.

Further, most systems currently used are designed to operate on acharacteristic ON-OFF" cycle. That is, when the thermostat or otherthermally sensitive element cools, it closes an electrical circuitwhich, in most cases, simultaneously or sequentially actuates the gasburner, the circulating pump, and a valve for the zone or zones to beheated. Since the water in the radiation system served by thisparticular thermostat has very likely already lost all or most of itsheat, the sudden inrush of hot water from the boiler often results incon siderable undesirable noise caused by the expansion of the pipes,and other elements of the radiation system.

This invention reduces or eliminates the noise problem in that itcontemplates that both the circulatory system and its correspondinggas-burner system are modulated so as to eliminate this characteristicON-OFF" cycle. That is, instead of cycling between ON and OFF, theproposed system automatically and simultaneously modulates both the gasflame and the rate of water circulation to substantially match the heatloss requirements of the zone affected. If, for example, the outsideambient is such that a conventional system would be ON for a period andthen OFF for a period, the system of this invention would automaticallyselect an intermediate flame or gas consumption rate, along with acorresponding intermediate hot water circulatory rate, and operate so asto make only infinitely small corrections of increase or decrease ineach rate as required. Such operation not only virtually eliminates allthermally induced noise, but it also substantially increases the overallthermal efficiency.

From the standpoint of operating economies, there is probably nothingquite so wasteful as a system requiring repetitious OFF and ON cycles,with its corresponding relatively cold fire box, followed by a highlycontrasting very hot fire box and its inescapable overdrafting. Thelatter condition continues for a considerable period of time after thestart of an OFF cycle because the stack temperature is so high that itcauses the interior air to be drawn up and out for several minutes aftercombustion has completely stopped. Not only does this remove asubstantial portion of the already heated room-temperature air fromwithin the structure, but it also excessively cools the boiler and stackat a very rapid rate, ejecting the now overheated air to the outsideatmosphere through the chimney. At the same time, a condition is createdsuch that reasonably proper combustion cannot again get underway untilthe next ON cycle has been in operation long'enough for the fire boxtemperature to come up to efficient operating temperatures, which is thereason that most heating engineers recommend against an installationwith a total heat capacity that is even slightly over and above thatwhich is absolutely required on the coldest day that can be anticipated.

It is known that continuous, uninterrupted operation of conventionalheating systems will provide maximum fuel economies, particularly onthose relatively infrequent very cold and windy days when the systemmust operate continuously to just barely replace the heat lost. Such anengineering compromise is of very little value, however, during thosemilder portions of the heating season when the heating system, becauseit is essentially too large" for such moderate weather, must necessarilycycle between ON and OFF, and it is of small comfort to thoseindividuals who would prefer to have at least some margin of safety forthe unpredictable, record-breaking, ultracold and windy day.

Equally important, it is not at all unusual for a conventional heatingsystem to break down or fail for any number of reasons, including anelectrical power or component failure. At such times, the building orother structure rapidly loses much ofits heat, and, only when the systemhas been repaired and restarted, is it often discovered that the systemmay be unable, even when operating at continuous full output capacityfor a reasonable period of time, to replace all the heat lost during theearlier shut-down period. By completely eliminating the electricalsystem, the invention eliminates virtually all of the major and mostfrequent causes of failure in heating systems, including failures inboth the source of the electricity and in the many electrically drivenor electrically activated components of existing conventional systems.

Another important problem associated with conventional heating systemsis the matter or personal comfort due to the excessive (some averageabout 3- /z F.) temperature differential required to cycle thethermostat. When the temperature in a zone must be raised 3- /z F. abovethe temperature where it last came ON before recycling the heatingsystem to OFF, the result is not only exceedingly uncomfortable, but itis also wasteful. It will be seen that the control apparatus of thisinvention is capable of holding the temperature variation of a givenclosed area to less than plus or minus 0. 1 F.

There are, of course, other problems and disadvantages with conventionalgas-fired, hot water heating systems, and a main object of the inventionis to provide such a system that is capable of operation by thecombustion gas alone, totally independent of electricity or othermechanical sources of power, either for circulation or automaticcontrol.

Another object of the invention is to provide such a system having twoprinciple circuits, a gas circuit and a water circuit, the gas circuitproviding the power for automatic control of water circulation.

Another object of the invention is to provide such a system wherein thewater is force-circulated by the compression energy contained in thecombustion gas.

Still another object of the invention is to provide such a systemwherein the heating capability of the water heating element isautomatically modulated to substantially match the heat loss of the areaor zone being heated.

Another object of the invention is to provide such a system wherein thewater circulation rate is automatically modulated to substantially matchthe heat balance between the water I heating element, and the heatradiating elements.

Another object of the invention is to provide such a system wherein thegas pressure modulating means operates on a balance between a primaryzone temperature responsive pressure and a secondary, adjustable,gravity-induced, heavy liquid pressure to control a gas pressure controlvalve.

A further object of the invention is to provide a novel gas pressureand/or flow control valve.

A still further object of the invention is to provide such a systemwherein the modulated gas pressure and/or flow is effective to modulatethe water circulation rate.

A further object of the invention is to provide such a system having anovel self-modulating gas burner construction.

A still further object of the invention is to provide such a systemwherein modulation of the gas pressure and/or flow affects automaticmodulation of the burner.

Another object of the invention is to provide such a system that isautomatically self-modulating so as to provide substantially infinitelyvariable or stepless heat gradients, eliminating thermally inducednoise, shock and vibration, as well as inefficiencies due to widelyvarying stack and combustion chamber temperature and/or inadequate orexcessive drafting.

Still another object of the invention is to provide such a systemcapable of highly consistent and stable temperature and comfort control.

Another equally important object of the invention is to provide such asystem that is dependable, efficient and less expensive to manufacture,install, and operate.

Another object of the invention is to provide such a system thatrequires essentially zero maintenance of any kind, except as might berequired to repair physical damage resulting from abnormal causes notrelated to operation of the system.

These and other objects and advantages of the invention will becomereadily apparent upon references to the following Detailed Descriptionand the attached drawings.

BRIEF DESCRIPTION OF THE VARIOUS VIEWS OF THE DRAWINGS FIG. 1 is adiagrammatic illustration ofa heating system embodying the invention,

FIG. 2 is an enlarged schematic elevational view illustrating the heatedzone temperature control and modulated gas supply portion of the systemshown by FIG. 1.

FIG. 3 is an enlarged top plan view ofa portion of FIG. 2.

FIG. 4 is an enlarged cross-sectional view of a portion of FIG. 2.

FIG. 5 is an enlarged cross-sectional view of a portion of FIG. 3.

FIG. 6 is an enlarged schematic elevational view of the water heatingburner and gas-lift, forced-circulation pump portion of the system shownby FIG. 1.

FIG. 7 is an enlarged cross-sectional view taken on the plane of line7-7 of FIG. 6, looking in the direction of the arrows.

FIG. 8 is an enlarged side elevational view, with portions thereofbroken away and in cross section, of the automatically self-modulatingwater heating burner of the system shown by FIG. 1.

DETAILED DESCRIPTION (A) General Structure Under this heading, thegeneral structure of the heating system will first be briefly described.The operation of the system and the structural details necessary orrelating to such operation will be discussed under the heading (B)Operation.

Referring now to the drawings in greater detail, and to FIG. 1 inparticular, a heating system 10 according to the invention includes agas circuit 12, indicated by tailed arrows, and a water circuit 14,indicated by the nontailed arrows, such designation of the gas and watercircuits being employed throughout the drawings. In the former circuit,gas flows from a regulated pressure source 16, through a gas flowcontrol valve 18, (shown in greater detail in FIG. 4), through thegaslift pump 20 (shown in greater detail in FIG. 6) and then to themodulated burner 22 (shown in greater detail in FIG. 8), the combustionproducts being discharged to atmosphere through the usual stack 24. Inthe water circuit 14, the pump 20 circulates water heated in theburner-boiler 22 to the radiators 26 in the heated zone 28 and back tothe burner-boiler 22.

Referring now to FIG. 2, the gas from the main (not shown) entersconduit 30, which may have manual valves 32 positioned on both sides ofany suitable gas pressure regulating valve 34. The conduit 30 alsoincludes a gas flow control valve 18, which, as shown in FIG. 4, maycomprise a conduit section 36 having an elastomeric sleeve 38 suitablymounted therein. The ends 40 of sleeve 38 may be rolled over the ends ofthe section 36, for example, and retained by means of rings 42 threadedon the ends 44 of the conduit 30. Any suitable means may be provided tocompress the elastomeric sleeve 38 to provide a gastight seal, and, inthe FIG. 4 structure, this is accomplished by the rings 42 drawing theconduit ends 44 axially toward the section 36 to compress the rolledsleeve ends therebetween. The rings 42 may be restrained axially by theannular beveled flange 46 on the section 36, and sealing compound,soldering or other known specific means may be employed to enhance thesealing.

The variable volume 48 between the elastic sleeve 38 and the rigidsection 36 communicates through a standpipe 50 with a reservoir 52containing a float valve 54 for at times closing the port 56 at the topof the reservoir so that the heavy liquid 58 contained therein and inthe standpipe 50 and the variable volume 48, for a purpose to bedescribed under Operation, cannot rise beyond the port 56. A hollowbellows assembly 35 having an opening 37 at its upper end may bethreaded or otherwise sealably secured into the section 36, the bellowsbeing adjustable axially by a screw 39 carried by a bracket 41 securedto the section 36, whereby liquid 58 within the bellows 35 may be, forexample, forced out to increase the height ofthe column 58 for controlpurposes.

Referring now to FIGS. 1-3 and 5, the zone or space to be heated 28,such as a room of a residence, may include a window 60 or other surface,and the room temperature rapidly decreases, during the heating season,as the window 60 is approached. A hollow pressure bulb 62 is mounted onthe wall 64 adjacent the window 60 on a pivot mechanism 66 and connectedby any suitable gastight means to a small conduit 68, which may bedisposed in the wall 64 and is connected by gastight means to thereservoir 52 at port 56. The bulb 62 and the conduit 68 contain a gasand/or liquid 70 that is not miscible with the heavy liquid 58 containedin the reservoir 52, and whose vapor pressure varies substantially withtemperature variations at the bulb which may be pivoted closer to thewindow when additional heat or a higher temperature is desired, and viceversa, as shown by the arrow 72.

While the operation of the system is described below, it will beapparent at this point that increased temperature at and pressure in thebulb 62 forces the heavy liquid level downwardly in the reservoir 52 andcauses the liquid 58 to constrict the elastic sleeve 38 and thus reducethe gas flow area therethrough. The converse is also true because theelastomeric sleeve 38 opposes such constriction and tends to retain amaximum flow area.

Referring now to FIG. 6, any gas passing through the sleeve 38 flowsfrom conduit 30 into the innermost vertical tube 74 of the gas-lift pump20, which further comprises an outer pipe or tube 76, which is closed atthe bottom and the open upper end 78 of which extends into the waterreservoir 80 and has formed on or attached thereto a conical ring 82 fora purpose to be described. Water 84 in the reservoir is replenished fromthe usual supply conduit 86, and a float valve 88, which is shown onlyschematically and may include any well-known levered structure adequateto close conduit against the water pressure therein, maintains the waterat any desired level, as at the level 90. The water leaves the reservoirby way of conduit 92, and it enters the pump at the bottom throughconduit 94.

An intermediate constant submergence" tube 96, open at its bottom andclosed at its top, is fitted with clearance over the inner tube 74 so asto receive gas therefrom, and it preferably may have secured at itsbottom end a plate 98 having small openings 100 therein for a purpose tobe described. The inverted intermediate tube 96, which is filled withgas, thus floats in the water contained in the outer tube 76. and it mayrise into the tube 102 extending from the top of the water reservoir 80.Gas thus flows from the inner tube 74 into the inverted tube 96,downwardly through the clearance 104 between the inner and the invertedtube, through the perforated plate 98, up through the water in theclearance 106 between the inverted tube and the outer tube, into thevolume 108 in the water reservoir 80 above the water level, up the tube102 and out the conduit 110 leading to the burner-boiler 22. Pumping ofthe water is, of course, accomplished by the gas rising and expanding inthe outer tube.

As shown in FIG. 6, heated water pumped into the reservoir 80 iscirculated bygravity through conduit 92 to the radiators or other heatradiating devices 26, which may be in series or parallel connection, andthen to the burner-boiler 22 through conduit 112 for heating and returnthrough conduit 9.4 to the bottom of the pump 20.

Reference is now made to FIG. 8, which is a substantially enlarged sideelevation, with portions thereof cut away and in cross section, of theburner-boiler 22 shown in FIGS. 1 and 6. It will be understood thatexcept for the specific structural features to be described, theburner-boiler 22 may be of any desired construction.

The burner-boiler is formed to include a fire box 114 having a stack 24and surrounded to any desired extent by a water chamber or boiler 118having a cold water inlet, conduit 112, and a hot water outlet, conduit94. The burner 120 is formed with an inclined passage 122 connected tothe gas supply conduit 110 and having a series of burner nozzle risers124 of progressively increasing height extending upwardly therefrom. Thelower end of the inclined passage 122 is connected by the conduit 126 tothe bottom of the control tank 128, the upper end of which is connectedby conduit 129 to a venturi restriction 130 in the gas supply conduit110 and which contains a float valve 132 for sealing the conduit, and bya branch conduit 134 to a fluid reserve tank 136 that may be refilledthrough nonvented plug 138.

The reserve tank 136 operates on the inverted container principle tomaintain the inclined passage 122 and nozzles 124 filled with a liquid140 to the level 142 only when gas flow is stopped; that is, the liquid140 will'be replenished to the intersection of conduit 134 with conduit126 whenever it drops below that level and when no gas is flowing. Whilethe nature and function of the liquid 140 will be described below, itshould be noted that increasing gas flow through the venturi restriction130 will cause a decreasing pressure in the control tank 128, thisincreasing pressure differential across the liquid 140 causing the level142 thereof to drop in the burner 120 and rise into the control tank128, thereby successively permitting additional nozzles 124 to-flow gasinto the fire box.

(B) Operation Temperature Control of Heated Space The temperaturecontrol mechanism employed in the proposed heating system uses an highlytemperature-sensitive gas/liquid 70 in combination with a static head ofheavy liquid 48 to modulate the flow of combustion gas through the gaslift, forced-circulation water pump 20, and thence to the modulated gasburner-boiler 22. The number of variations which may be employed withthis type of control mechanism is virtually unlimited, but only onespecific example will be described in detail, for purposes ofillustration.

It is first necessary to consider some of the more pertinent andcritical objectives of such a system. Since the combustion process isitself modulated without frequent recourse to the extremes of either ONor OFF, it is necessary that some specific temperature control range beselected as representative of these two extremes. In this specificexample, 72 F. has been selected to be normal, with provision that atemperature rise of O.5 F. will completely stop the water pumping andgas combustion process, whereas a drop of 0.5 F. will cause combustiongas flow and pumping to be at design maximum, which in this case hasbeen arbitrarily selected to be 60,000 B.t.u.s/hr. input or one cubicfoot of gas/min. for a typical single heated zone installation. Thisinput capacity can, of course, be modified as necessary by the designengineer.

In other words, a control temperature range of l.0 F. should govern theentire gas-flow range from zero to the design maximum. In practice itwill be found that this is capable of holding the temperature of a givenheated space to within plus or minus 0.05 F., provided, of course, thatthe total output capacity of the burner is equal to or in excess of themaximum heat loss that can be expected on the coldest and/or windiestday anticipated.

Beginning in the heated zone 28, the control system consists of a smallpressurized bulb 62 containing a suitable gas and/or fluid 70 andmounted on a pivot 66 that is attached to the wall or ceiling 64 so thatit can be moved into and out of slightly higher or lower temperatures,as, for example, close to the window 60 or other similarly cooler area,or away from such an area and into inherently warmer areas, includingpositions immediately above or close to the zone heat radiation devices.This is the only normal manual adjustment of temperature controlavailable in the system 10 for actuation within the heated spaceinvolved, but the liquid column in standpipe 50 (secondary heavy-liquidcontrol column to be discussed later) may be constructed so that it canalso be adjusted (screw 39 in FIG. 4), thereby offering two independentforms of manual control.

Using the single control, if an increase in temperature were desired,for example, the pressure bulb 62 would be moved closer to a window 60or other similarly cooler area; if a temperature decrease were desired,the bulb would be moved away from the cooler area into a normally warmerlocation. Since the temperature variation within only a few inches of awindow may be quite pronounced, it will be found that the required bulbmovement will usually be quite small. The bulb motion could, if desired,be calibrated to reflect simulated or actual temperature settings.

In order that the bulb 62 may be moved or swiveled in and out on itspivot 66, it is necessary that a highly durable flexible tubing 69 or anabsolutely gastight swivel fitting 66 be provided for the connection ofthe bulb to the tubing 68 permanently installed and concealed within thewalls 64. The tubing may be quite small, and ordinary one-sixteenth inchcommercial copper tubing is adequate. The other end of the tubing 68connects with the top of a relatively small diameter vertical standpipeor column 50 containing a predetermined static head" of some suitableheavy liquid 58 with low vapor pressure characteristics and completelynonmiscible with the gas/ liquid 70 used in the pressure bulb. Theinternal volume of the connecting tubing 68 should be small in relationto the volume of the pressure bulb 62. Wherever it is practicable to doso, the tubing 68 should be routed so as to not pass through or near anyhot areas as this can adversely affect uniformity of control,particularly if such areas are subject to considerable temperaturevariations that do not necessarily parallel temperature variationswithin the heated zone. The column of heavy liquid 58 communicates withand operates the flow valve 18controlling gas flow, as shown in FIGS. 2and 4. The height of the column of liquid 58 is inversely proportionalto its specific gravity, i.e., a fluid with only half as much specificgravity would require a column height or head" twice as high.

If Freon ll (CCl F) is used as the primary control gas/liquid 70, thenthe height of the secondary heavy liquid column 50 should be such thatwhen a vacuum of exactly 0.575 p.s.i.g. (when atmospheric pressure isstandard or 14.7 p.s.i.a.) or an absolute pressure of 14.125 p.s.i.a.(when atmospheric pressure is standard) exists in conduit 68 con nectedto the top of the column, the weight of the liquid 58 is just sufficientto completely constrict the sleeve 38 and stop all gas flow against theregulated input gas pressure in conduit 30. Further, the cross-sectionalarea and the volume above the liquid column 58 should be such that allor most of the heavy liquid 58 is withdrawn from the gas-flow controlvalve chamber 48, so as to permit maximum gas fiow, when the vacuum isincreased to 0.865 p.s.i.g. or to an absolute pressure of 13.835 whenatmospheric pressure is 14.7 p.s.i.a.

Since these pressure values may be too critical for equipment andinstrumentation available to most installation personnel, this problemcan be greatly simplified by merely using a transparent tubing 50 forthe vertical column and affixing thereto, or inscribing thereon,specific levels to which the liquid 58 should be initially filled,together with an indication as to the exact amount of liquid that shouldbe added after the action of valve 18 has been checked to insurecomplete constriction of sleeve 38 and gas-flow stoppage when the upperend of the column 58 is open to the atmosphere prior to its beingconnected to the control gas/liquid in bulb 62 and conduit 68.

Additional desirable fine adjustment is made possible by the screw 39 tovary, within design limits, the height of the heavy liquid column. Itshould be noted here that a normal heated zone temperature of 72 F. willgive Freon 11 a pressure of approximately 13.98 p.s.i.a., or about 0.72p.s.i.g. below atmospheric pressure, and that this reduced pressure willtend to reduce the sleeve constricting pressure in the gas-flow controlvalve 18 by an equal amount.

The elastomeric sleeve 38 in the gas-flow control valve 18 should be onethat is completely impermeable and totally unaffected by the gas usedfor combustion or by the control liquid 58 used in the vertical column.lt should also possess good elastic recovery properties, along with verylittle tendency to acquire a permanent set. Such requirements narrow thefield somewhat so as to eliminate almost all known elastomers with theexception of certain of the silicones and polyurethanes. The elastomericsleeve 38 should be assembled or installed with sufficient initialstretch" so as to be capable of expulging all of the control liquid 58from the valved chamber 48 without any assistance from gas pressurewithin the sleeve, and with the heavy liquid control column 50disconnected.

It will thus be apparent that a combination of three forces tend tomaximize combustion gas flow. These forces are (a) the elastic recoverycapabilities of the elastomeric sleeve 38 in the gas flow control valve18, (b) the combustion gas pressure itself and (c) the absence ofpressure" or partial vacuum in the primary gas/liquid (bulb 62) controlsystem. The latter force amounts to 0.29 pound per square inch (0.29psi.) for the entire l F. operating range, plus an additional 0.575p.s.i. to account for the reduction below atmospheric pressure whenFreon 11 is at 725 F. which is the upper limit of the control range.

It is further apparent that the incoming combustion gas pressure is, byfar, the largest of the forces involved. In designing the heating system10, certain realistic values should first be assumed for the purpose ofmaking a trial computation. Thus, let it be assumed that the inputcombustion gas pressure is p.s.i.g., that the primary gas/liquid controlpressure variation (over 72.572.5) is 0.29 p.s.i.g. and that the elasticrecovery forces in the gas-flow control sleeve 38, when translated intothe hydraulic pressures generated by the secondary heavy liquid column58, are 0.39 p.s.i.g. when the sleeve is fully extended inwardly to theposition wherein gas flow is completely stopped and 0.1 p.s.i.g. when itis fully contracted so as to permit maximum combustion gas flow. Thisestablishes the two extreme critical pressures on the hydraulic side ofthe elastomeric sleeve 38, i.e. 5.39 p.s.i.g. when combustion gas flowis stopped, and 5.1 p.s.i.g. when gas flow is at a maximum.

The above 0.29 p.s.i.g. differential (5.395. 1) corresponds to theworking pressure variation in the primary gas/liquid pressure controlsystem. It means that the height of the heavy liquid 58 in the secondarypressure control system acting to constrict the combustion gas controlvalve sleeve should be such as to produce a pressure of 5.39 p.s.i.g.plus 0.575 p.s.i.g. additional to compensate for the pressure reductionin Freon 11 when it is at 725 F., or a total of 5.965 p.s.i.g. acting onthe sleeve when the top of the secondary pressure control column is opento atmospheric pressure. If this liquid were water (not recommended),the height of the filled portion of the column 50 should be 5.9652.3l=l3.779l5 or approx. 13.78 feet.

The volume of the reservoir 52 should be sufficient to accommodate allof the liquid 58 within the control sleeve 38 when the conduit 68 isconnected to the reservoir and the primary gas/liquid control pressuretherein is a vacuum of 0.865 p.s.i.g. or more. A float-type check valve54 should be provided in the reservoir 52, or at the top of thesecondary pressure control system, so as to prevent any ofthe heavysecondary control liquid from overflowing F., the primary system whenthe primary control pressure is more than 0.865 p.s.i.g. belowatmospheric pressure. If no such check valve were provided, suchoverflow back into the primary system could happen, for example, if theheating plant were to be shut down so that there is no combustion gaspressure acting on the sleeve 38 and the normally heated zone where theprimary pressure control bulb 62 is located might become quite cold.

Should a given sleeve construction and elastomeric composition be foundto require too much pressure for actuation under optimum conditions, itmay be stretched more tightly by lengthening the tube 36 on which it ismounted, and the liquid withdrawal volume above the hydraulic fill linein the secondary pressure control system should be increasedaccordingly. It is preferable that this withdrawal volume be asubstantially enlarged section of the secondary pressure control tubing,like the reservoir 52, so as to provide room for the check valve float,and to reduce the overall height requirements for withdrawal.

The overall height requirements may be further reduced by using a liquidheavier than water, or water containing some soluble material such ascalcium chloride, whereby the specific gravity may be increased to about1.54 in a saturated solution. In the earlier example where waterrequired an initial fill height of some 13.78 ft., this can be reducedto 5.965X2 .3l/1.54= D/4*-" or approx. 8.95 ft. However, the use of CaClsolution will require that the tube 36 in which the elastomeric sleeve38 is mounted be adequately protected on its inner surface with somematerial not adversely affected by a calcium chloride solution. CaCl hasthe advantage of being readily available at low cost, and it providesadequate protection against freezing. There are numerous other heavy(heavier than water) nonfreezing liquids which may also be adapted touse in this system, however.

Gas-Lift Forced-Circulation Water Pump As previously stated, theforced-circulation water pump 20 operates on the gas-lift principle,using the pressure already available in the combustion gas. Combustiongas passing through the flow-control valve 18 is made to enter the baseof a vertical water pumping tubelike apparatus 20, the diameter of theouter tube 76 being greatly exaggerated in size in the drawings forclarity. The gas then passes upwardly through the smaller tube 74 whichterminates at some intermediate height which will be more accuratelydefined. The inverted tube 96 encloses the first tube 74, and it servesthe function of causing combustion gas to be discharged into thecirculating water at some predetermined constant submergence depth. Thisis necessary in order to maximize water volumetric flow, since thegasepressure required to start the pumping operation from some givensubmergence depth is greater than the pressure required to keep thepumping action going once it is started. Stated in another way, thewater level between the main pump casing 76 and the gas-filled constantsubmergence tube 96 will, when no gas is flowing, normally be very nearthe top of the main casing 76, about midway in the overflow tank orwater reservoir 80, as at 90. The cone at the top of outer tube 76 isprovided to prevent the noise of falling water.

When pumping action begins, the small gas bubbles, formed in part by theapertured plate 98 attached to the open bottom end of tube 96,intermingle with the water so that the combined weight of the water andgas mixture above the bottom of the constant submergence tube will beconsiderably less than it would if the gas bubbles were not present.Since the constant submergence tube floats in this water, it cannotfloat as high when the weight of the flotation water is reduced byintermixed gas bubbles, and consequently it sinks to a lower level. Thenet effect is to insure that the gas will always exit from the base ofthe constant submergence tube at or very near the design operating gaspressure as controlled by the automatic pressure-reduction valve 34. Asa specific example, if the operating combustion gas pressure isp.s.i.g., then the distance from the normal static water level 90, whenno gas is flowing, to the bottom of the constant submergence tube aplate 98 should be just under 5X2.31=1 1.55 ft. ln other words, theconstant submergence tube 96 should be ballasted to float submerged tothis depth.

To maximize efficiency, the constant submergence tube 96 should betapered so that its distance is slightly smaller at the top, or theouter casing 76 should be similarly but oppositely tapered so that itsdiameter is slightly larger at the top. The amount of this taper is muchtoo small to be shown in the drawings; however, it can be calculated onthe basis that the cross-sectional area at any elevation of thegas-water flow should be equal to the combined volumes of gas and waterat that elevation, it being clear that the rising gas is constantlyexpanding because its submergence depth is steadily decreasing. Thesmallest cross-sectional area for the gas-water mixture should be, insquare inches, equal to the gallons of water flow/min. divided by K2.

Pumping will be more efficient if the water is raised at a steadyuniform flow rate rather than at a continuously accelerated rate, and auniform flow rate can be attained by incorporating a suitable expansiontaper into the design. The efficiency is further enhanced by attachingthe finely perforated plate 98 to the bottom of the constant submergencetube 96 to divide the gas into smaller bubbles because larger bubblesoffer a somewhat lesser amount of total surface area for contact orcohesion with the water.

The amount of water than can be pumped by this gas-lift method isdependent upon many variables, not the least of which is the totalresistance to flow offered by the radiation system and its connectingpiping to and from the boiler room. lt is essential that the hydrostatichead" or pressure of the water pumped be such as to overcome this flowresistance to the extent that the return water flow to and through theboiler 22 and then to the base of the gas-lift pumping assembly will beat a rate sufficient to replace the water in the gas-lift column withinouter pipe 76 without an excessive amount of pull-down on the constantsubmergence tube. Should tube 96 bottom," it is clear that thecombustion gas could exhaust from its base at a much higher rate becauseof the reduced resistance resulting from a decrease in the effectiveweight of the overlying water, and as a consequence the amount of wateractually circulated would be reduced.

The total volumetric water flow required is primarily related to theheat input to the boiler 22, and secondly to the heat output through theradiation system. On the input side, one cu. ft./min. or 1000B.t.u.s/min. was previously hypothetically assumed as an operatingmaximum for a typical single heating zone installation. If the boiler 22is 80 percent efficient, then ill some 800 B.t.u.'s/min. will enter thewater. if the boiler contained only 8 lbs. or just slightly under onegal. of water, the temperature of this 8 lbs. of water would be raisedF. say from 100 F. to 200 F., and it would necessary that this water bereplaced once/minute, i.e., the required minimum water circulation wouldbe approx. one gal./min. This situation would, of course, also requirethat the radiation system be capable of losing 800 B.t.u.s/min., but itmight be extremely difficult or impracticable to distribute or spreadout" only 8 lbs. of water over a large enough area as to be able to lose800 B.t.u.s/hr. It is therefore preferable that the volume of waterpumped be greater than 8 lbs/min.

Fortunately, the gas-lift system is capable of pumping considerably morewater, just how much more depending upon several factors, including thetotal lift height. The maximum lift height is limited by the effectivegas pressure. In the construction of the proposed system 10, it can beseen that there is an over-pressure imposed upon the water pumpingsystem which is greater than atmospheric pressure, but less than the sumof atmospheric pressure plus the incoming gas pressure, the amount ofthis over-pressure" depending upon the rate of gas flow through theburner 120. That is, if the gas flow is restricted only a small amount,then the over-pressure" will be relatively low. If the burner orifices124 are substantially the same as those presently used in the so-calledlowpressure systems, i.e., for operation at about 0.25 p.s.i.g., and ifthe pressure drop due to friction in the pipes leading from the top ofthe water pump 20 to the burner is another 0.25 p.s.i.g., then theover-pressure could be approximately 0.5 p.s.i.g. If the incoming gas isat 5 p.s.i.g., and if the pumping system were 100 percent efficient,then 1 cu. ft. of gas/min. at 5 p.s.i.g. could lift 1 cu. ft. of water adistance of2.3 l (50.5) =l0.395 or approx. IOVsft. Since such systemsare only about 50 percent efficient, the amount of water would be halvedso that 1 cu. ft. gas/min. at 5 p.s.i.g. would lift (7.48/2) =3.74gals/min. to a height of 10%1ft. With an overpressure of 0.5 p.s.i.g.,the constant submergence tube 96 should be ballasted to float at a depthof approx. IO /sft. instead of the l 1.55 feet previously indicated.

This l0 /aft. submergence depth also represents the effective pressurehead for the circulation of water except that there is a small lossbecause of the need to insure that the water level in the overflow tankis always a few inches lower than the top of the pump outlet. Fourinches or Va ft. should be adequate for this purpose, and this leaves aneffective pumping head" of 10 ft. or (l0/2.3l)=or about 4.33 p.s.i.g.for water circulation, which should be adequate for most 60,000B.t.u./hr. single heated zone installations.

It should be noted here that it is not essential that the incoming gaspressure be limited to only the 5 p.s.i.g. used in'the precedinghypothetical installation, and many modern gas companies are alreadyequipped to supply gas at pressures up to 50 p.s.i.g. or more. lt can beseen that if the incoming gas pressure were to be increased to l0p.s.i.g., for example, and if the burner construction and the pipefriction loss were the same, then the pressure available for watercirculation could be increased to 2.3l(100.5) -l/4 =2l.695 ft. or apressure of (2 l .695/2.3 l =9.39 p.s.i.g. (approx.) for circulation.Such a pressure increase would, of course, require that the secondary(heavy liquid) pressure control system be approximately redesigned,together with the substitution of an appropriate pressure-reductionvalve 34.

It should be noted here that as the water temperature increases, itdecreases in weight (to 8.039 lbs/gal. at 200 F.) and therefore liftseasier; at the same time, the pumping gas is expanded due to increasedtemperature so that its volume is increased substantially to furtherincrease the amount of water pumped.

Some water vapor is lost in this system because it mixes with thecombustion gas and enters the combustion chamber. This is more of anasset than a liability, however, because this substantially improvedthermal conductivity and heat transfer between the hot combustion gasesand the water chamber of the burner-boiler 22, accordin g to numerousresearchers, including several U.S. Government laboratories.

The heat gained by the combustion gas when passing through the pump isnot lost since it is returned to the combustion chamber 114 if theconnecting lines are suitably insulated. In fact, the entire pumping,overflow tank, boiler, and all associated lines should be properlyinsulated to minimize losses.

Automatically Self-Modulating Gas Burner Referring to FIG. 8, burner 120employs a high-temperature, exceptionally low-vapor pressure liquid 140having high cohesion and low adhesion properties as the modulationcontrol media. For example, some of the high temperature siliconelubricants are well-suited to this application. When the burner isinoperative, i.e., when no gas is flowing in conduit 110, the controlliquid 140 seeks the horizontally level position 142. The reserve tank136 provides replenishment fluid as required, even though the amount offluid expected to be consumed has been calculated to be extremely low,probably less than 0.01 gal./year for an average 60,000 BTU/hourinstallation. it will be noted that the temperature of liquid 140 isnever very high, in spite of its close proximity to the fire box 114,since the burner 120 is cooled by both the incoming gas and the air usedfor combustion. As stated previously, certain details of theburner-boiler 22 are of no significance to the invention, among thesebeing the combustion air supply, which is not shown except for the airjets represented at 125. Further, FIG. 8 illustrates a sectional view ofa single row of burner nozzles 124, and it will be understood that theburner 120 could have any desired number of rows of nozzles 124, in avariety of configurations.

The reserve tank is of the inverted container type so that the fluidlevel 142 in the burner control system will be held constant, and itwill be noted that filling can only occur when the burner 120 isinoperative and when the fluid level 142 is below the level of theconnection (conduit 134) to the reserve tank 136.

As shown in FIG. 8, when combustion gas is flowing at a very slow rate,only the three burner nozzles 124 at the extreme left (FIG. 8) willignite (the pilot light for ignition is not shown) and be operative.Three nozzles are a purely arbitrary consideration, and only one or anynumber of nozzles may be used for the lowest operating condition justabove completely OFF. It will be recognized that the orifice size ofthese in dividual burner nozzles 124 will largely dictate the number tobe activated in the lowest heating condition.

Even when combustion gas flow is at a predetermined minimum, there willgenerally be enough pressure in the burner assembly 120 to cause thefluid 140 at the extreme left in passage 122 to depress slightly, whileconcurrently causing the fluid in all nozzles 124 except the first threeon the left to raise even less slightly since the fluid volume decreaseon the left will be distributed equally among all the other inactivefluid columns or nozzles 124 plus the control column in conduit 126 onthe extreme right.

As combustion gas flow is increased, its passage through the venturi 130in conduit 110 will tend to generate a gradually increasing vacuumtransmitted to the top of the control tank 128, which normally would beinsulated from the burnerboiler 22. As the vacuum increases, fluid 140is withdrawn from the burner 120 control assembly, until none remainswhen gas flow is at a design maximum. Thus, the venturi 130 should beselected on the basis of its ability to lift all of the fluid 140 intothe control tank 128 until the last burner orifice 124 at the extremeright is uncovered" and operating.

The float valve 132 in the control tank is for the purpose of providingsafety against the possibility that gas flow might in some mannerinadvertently exceed the design maximum, and thus tend to pull thecontrol liquid 140 up and over into the venturi. This could do no realdamage, of course, since the fluid 140 would merely fall back downthrough the gas inlet conduit 110. However, there is some possibilitythat a condition could exist wherein the reserve tank 136 might becaused to overfill the system, and this could either cause the entireburner assembly to shut down or cause some of the liquid to passupwardly through the nozzles and spill over into the combustion airinlet openings 125. The float valve is therefore considered to bereasonably essential. It should be noted here that the volume of thecontrol tank 128 with the float 132 against its seat 127 should be equalto the volume of fluid required to fill the burner control assembly fromthe bottom of the standpipe conduit 126 to the design fluid level 142when no or minimum gas is flowing. To allow for normal manufacturingvariations, this volumetric relationship may be finely adjusted at thetime of installation by moving the float valve seat 127 up or down, orby the addition or removal of spacer washers (not shown) as necessary.

It will be apparent from the above-description, wherein the inventionhas been disclosed in such clear and concise terms as to allow thoseskilled in the art to practice the same, that the invention provides anautomatic, self-modulating, gasflred, gas-powered, forced-circulationhot water heating system that requires no electrical power and ischaracterized by the numerous initially-stated objectives, as well asproviding other advantageous results.

While the invention has been shown and described as embodied in a hotwater heating system, certain portions thereof are applicable to anysystem, such as a forced air system, as well as for other uses.

To those skilled in the art to which this invention relates, manyvariations in construction and widely differing embodiments of theinvention will suggest themselves without departing from the spirit andscope of the invention. Thus, the disclosures and description herein arepurely illustrative and are not intended to be in any sense limiting.

lclaim:

1, Apparatus for controlling volume rate of fluid flow throughassociated fluid supply conduit means in accordance with the temperatureof a related zone, comprising variable throttling means in circuit withsaid supply conduit means, and thermally expansible means responsive tothe temperature of said related zone and operatively connected to saidvariable throttling means, said thermally expansible means beingeffective to vary the opening of said variable throttling means toregulate the volume rate of flow of said fluid therethrough in relationto the magnitude of said temperature of said related zone, said variablethrottling means comprising a rigid conduit having a high-recoveryelastomeric sleeve therein, said sleeve having the ends thereofconnected to said rigid conduit and the intermediate portion thereoffree therefrom thereby defining a generally annular chamber between saidright conduit and sleeve, and said thermally expansible means comprisingmeans for communicating a variable pressure developed externally of saidannular chamber and dependent upon said temperature of said related zoneto said annular chamber to variably constrict said sleeve and therebydetermine a variable flow area controlling the volume rate of flow ofsaid fluid in accordance with said temperature of said related zone.

2. Apparatus for controlling volume rate of fluid flow according toclaim 1, wherein said fluid comprises a gas.

3. Apparatus for controlling volume rate of fluid flow according toclaim 1, wherein said annular chamber contains a second fluid for thetransmission of said variable pressure developed externally of saidannular chamber, and standpipe means communicating with said annularchamber, said standpipe means containing said second fluid therein to apreselected height when said sleeve is constricted to a correspondingpreselected flow area.

4. Apparatus for controlling volume rate of fluid flow throughassociated fluid supply conduit means in accordance with the temperatureof a related zone, comprising variable throttling means in circuit withsaid supply conduit means, and thermally expansible means responsive tothe temperature of said related zone and operatively connected to saidvariable throttling means, said therrnalfie pansible means beingeffective to vary the opening of said variable throttling means toregulate the volume rate of flow of said fluid therethrough in relationto the magnitude of said temperature of said related zone, said variablethrottling means comprising a variable flow area conduit section, saidconduit section comprising a generally annular wall radially deflectableto define internally thereof said variable flow area, a generallyannular pressure chamber formed about and radially outwardly of saidannular wall, a first fluid pressure medium contained within saidpressure chamber for applying a variable pressure against said wall inorder to effect deflection thereof, and said thermally expansible meanscomprising a second fluid pressure transmitting medium situatedexternally of said annular pressure chamber communicating with saidfirst fluid pressure medium in order to at times apply an increasingpressure to said first medium and thereby cause increased deflection ofsaid wall and a reduction in the effective area of said variable flowarea.

5. Apparatus for controlling volume rate of fluid flow according toclaim 4, wherein said second fluid pressure medium creates saidincreasing pressurehi said first fluid medium by undergoingsubstantially only volumetric displacement in accordance with thetemperature sensed at said related zone.

6. Apparatus for controlling volume rate of fluid flow according toclaim 5, wherein said thennally expansible means also comprisestemperature responsive closed pressure means, said closed pressure meanscomprising a container filled with a temperature responsive gas whosevapor pressure varies substantiaily with the temperature of said relatedzone, said gas being operatively placed in communication with saidsecond fluid medium and effective upon sensing an increase oftemperature at said related zone causing said volumetric displacement ofsaid second medium.

7. Apparatus for controlling volume rate of fluid flow according toclaim 1, including adjustment means associated with said annularchamber, said adjustment means comprising a second chamber communicatingwith said annular chamber and being adjustably volumetricallycollapsible.

1. Apparatus for controlling volume rate of fluid flow throughassociated fluid supply conduit means in accordance with the temperatureof a related zone, comprising variable throttling means in circuit withsaid supply conduit means, and thermally expansible means responsive tothe temperature of said related zone and operatively connected to saidvariable throttling means, said thermally expansible means beingeffective to vary the opening of said variable throttling means toregulate the volume rate of flow of said fluid therethrough in relationto the magnitude of said temperature of said related zone, said variablethrottling means comprising a rigid conduit having a highrecoveryelastomeric sleeve therein, said sleeve having the ends thereofconnected to said rigid conduit and the intermediate portion thereoffree therefrom thereby defining a generally annular chamber between saidright conduit and sleeve, and said thermally expansible means comprisingmeans for communicating a variable pressure developed externally of saidannular chamber and dependent upon said temperature of said related zoneto said annular chamber to variably constrict said sleeve and therebydetermine a variable flow area controlling the volume rate of flow ofsaid fluid in accordance with said temperature of said related zone. 2.Apparatus for controlling volume rate of fluid flow according to claim1, wherein said fluid comprises a gas.
 3. Apparatus for controllingvolume rate of fluid flow according to claim 1, wherein said annularchamber contains a second fluid for the transmission of said variablepressure developed externally of said annular chamber, and standpipemeans communicating with said annular chamber, said standpipe meanscontaining said second fluid therein to a preselected height when saidsleeve is constricted to a corresponding preselected flow area. 4.Apparatus for controlling volume rate of fluid flow through associatedfluid supply conduit means in accordance with the temperature of arelated zone, comprising variable throttling means in circuit with saidsupply conduit means, and thermally expansible means responsive to thetemperature of said related zone and operatively connected to saidvariable throttling means, said thermally expansible means beingeffective to vary the opening of said variable throttling means toregulate the volume rate of flow of said fluid therethrough in relationto the magnitude of said temperature of said related zone, said variablethrottling means comprising a variable flow area conduit section, saidconduit section comprising a generally annular wall radially deflectableto define internally thereof said variable flow area, a generallyannular pressure chamber formed about and radially outwardly of saidannular wall, a first fluid pressure medium contained within saidpressure chamber for applying a variable pressure against said wall inorder to effect deflection thereof, and said thermally expansible meanscomprising a second fluid pressure transmitting medium situatedexternally of said annular pressure chamber communicating with saidfirst fluid pressure medium in order to at times apply an increasingpressure to said first medium and thereby cause increased deflection ofsaid wall and a reduction in the effective area of said variable flowarea.
 5. Apparatus for controlling volume rate of fluid flow accordingto claim 4, wherein said second fluid pressure medium creates saidincreasing pressure in said first fluid medium by undergoingsubstantially only volumetric displacement in accordance with thetemperature sensed at said related zone.
 6. Apparatus for controllingvolume rate of fluid flow according to claim 5, wherein said thermallyexpansible means also comprises temperature responsive closed pressuremeans, said closed pressure means comprising a container filled with atemperature responsive gas whose vapor pressure varies substantiallywith the temperature of said related zone, said gas being operativelyplaced in communication with said second fluid medium and effective uponsensing an increase of temperature at said related zone causing saidvolumetric displacement of said second medium.
 7. Apparatus forcontrolling volume rate of fluid flow according to claim 1, includingadjustment means associated with said annular chamber, said adjustmentmeans comprising a second chamber communicating with said annularchamber and being adjustably volumetrically collapsible.